Component assembly cushioning device for mobile devices

ABSTRACT

A spacer for use in a mobile device fills the space between a component assembly and a housing. The spacer includes a layer of compressible material for insertion between the component assembly and the housing. A plurality of compressible features are provided on a face of the layer. Upon insertion of the component assembly and assembly of the housing, the compressible features are compressed to fill a gap between the component assembly and the housing without over-compressing the main body of the spacer, allowing the body of the spacer to cushion any subsequent impact to the mobile device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/625,872, filed Jan. 23, 2007, which is a division of U.S. patentapplication Ser. No. 10/890,325, filed Jul. 14, 2004, which in turnclaims the benefit of priority from GB Patent Application No. 0316451.4,filed Jul. 14, 2003. Each of these prior applications is herebyincorporated by reference, in its entirety, into this application.

FIELD

The present invention relates to a mobile devices and particularly, to adevice for cushioning a component assembly in a mobile device.

BACKGROUND

Many mobile electronic devices such as hand-held computers, cellulartelephones, personal digital assistants (PDAs), have a multi-componentassembly housed within a small case or housing. A small housing meansthat a small change (numerically) in the size of the internal componentsor the housing can result in a large change (in terms of percentage) inthe space within the housing allocated for the component assembly. Atypical component assembly is a component stack that includes a display,such as a liquid crystal display (LCD) and a circuit board.

Typically, the housing consists of two mating halves to contain theassembly. The mated halves define an interior cavity and, of course, thedepth of the component assembly must be slightly less than the depth ofthe interior cavity. The difference in depth results in an undesirablegap between the component assembly and the housing inside the assembleddevice.

The gap can be expected to vary in depth due to manufacturingtolerances, assembly tolerances, substitution of components in thecomponent assembly, redesign of the component assembly or the use of astandard housing for different models or devices.

The gap is undesirable since it can result in movement or play of theinterior components of the device allowing components to becomedisplaced, disconnected, damaged or simply rattle around inside thehousing, especially if the device suffers a shock such as from beingdropped.

To eliminate these undesirable results, one solution is to employ acushion or spacer, for example, a layer of compressible foam. Initially,the uncompressed spacer is deeper than the dimension of the gap so thatwhen the depth of the spacer is added to the depth of the componentassembly, the total depth is greater than that of the interior of thehousing. However, during assembly of the housing of the device, theinterior of the housing comes into contact with the spacer andcompresses it against the component stack. Accordingly, the gap isoccupied by the compressed spacer preventing movement of the componentassembly in the direction of the stack-up (normal to the plane of thecircuit board or the LCD).

If the spacer is insufficiently deep, it will not span the gap even inan uncompressed state or it will provide inadequate cushioning for thecomponent assembly. If the spacer is too deep then upon compression itwill exert excessive pressure to the component assembly including thedisplay. In the situation where the display is an LCD module, the LCDitself is sensitive to the pressure applied to it. Pushing it unevenlyor with too much force will cause a blemish or distortion to appear inthe viewing area. Excessive pressure can also prevent the spacer fromproperly dispersing the energy of an impact because its ability todeflect has already been used in taking up the tolerance of the smallavailable space and in extreme cases excessive pressure or the inabilityto deflect a shock can result in breaking of the screen. This is verycostly, especially if the screen is an expensive colour LCD.

Any of these scenarios can result in an unacceptable product andincrease the cost of manufacturing of mobile devices. Accordingly, it isdesirable to provide an improved spacer for use with a componentassembly to more controllably fill a gap between the component assemblyand the housing.

SUMMARY

According to an embodiment, there is provided a spacer for use in amobile device to space a component assembly from a housing of the mobiledevice. The spacer comprises a body of compressible material forinsertion between the component assembly and the housing; and aplurality of compressible features provided on the body. Thecompressible features deform to prevent displacement of the componentassembly relative to the housing while leaving the body of the spacerrelatively uncompressed so that the body cushions the componentassembly. The compressible features can be domed, cylindrical, polygonalprism, conical, frusto-conical, pyramidal or frusto-pyramidal in shape.

According to a further embodiment, there is provided a spacer for use ina mobile device. The spacer fills a space between a component assemblyand a housing. The component assembly includes a display component. Thespacer comprises a layer of compressible material for insertion betweenthe component assembly and the housing; and a plurality of compressiblefeatures provided on a face of the layer. The compressible features arecompressible upon assembly of the mobile device and extend between thecomponent assembly and the housing to space the component assemblyinside the housing when the mobile device is assembled. The depth of thelayer and uncompressed compressible features exceeds the depth of thespace between the component assembly and the housing, and the depth ofthe compressed layer and the compressed compressible features exceeds apredetermined critical depth.

In another embodiment, there is provided a method of manufacturing aspacer for use in a mobile device. The spacer includes a body ofcompressible material for insertion between a component assembly of themobile device and a housing of the mobile device; and a plurality ofcompressible features are provided on the body for filling space betweenthe component assembly and the housing during assembly of the mobiledevice while leaving the body of the spacer relatively uncompressed sothat the body can cushion the component assembly. The method comprisessteps of depositing partially cured solution of material onto a surface;spreading the partially cured solution of material to form a layer ofdesired thickness; using a patterned roller to flatten and pattern thespread partially cured solution of material; and allowing the partiallycured solution of material to cure.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way ofexample only, with reference to the attached drawings, wherein:

FIG. 1 is an exploded view of a mobile device including a spaceraccording to an embodiment of the present invention;

FIG. 2 shows an alternative embodiment of the present invention;

FIG. 3 shows another alternative embodiment of the present invention;

FIG. 4 shows a section view along the line 4-4 of FIG. 3;

FIG. 5 is an exploded view of a mobile device including two spacers;

FIG. 6 shows a section view of a further embodiment of the presentinvention;

FIG. 7 shows a still further embodiment of the present invention;

FIG. 8 is a section view of an additional embodiment of the presentinvention;

FIG. 9 shows a graph illustrating relationship between force anddisplacement;

FIG. 10 shows a graph contrasting the compression properties of a spaceraccording to embodiments of the present invention with those ofconventional technology;

FIGS. 11 a and 11 b show the range of gaps accommodated by aconventional spacer;

FIGS. 12 a and 12 b show the range of gaps accommodated by a spaceraccording to embodiments of the present invention;

FIGS. 13 a, 13 b and 13 c show the deformation of a spacer incompression;

FIGS. 14 a, 14 b and 14 c show the steps in a method of manufacturing aspacer; and

FIG. 15 shows the master roll 1440 of FIG. 14.

DETAILED DESCRIPTION

Generally, a spacer for use with a mobile device having a componentassembly enclosed in a housing is provided. The spacer occupies a gapbetween the component assembly and the housing.

Referring to FIG. 1, a mobile device 100 has a component assembly orcomponent stack contained within a housing. The mobile device 100 is anelectronic device such as a hand-held computer, a cellular telephonewith or without data communications functionality, a wireless mobiledata communication device, a wireless email communication device, apager, or a PDA, for example. The housing of FIG. 1 consists of twomating halves, a front half 110 and a back half 150. When the front andback halves are assembled, they define the housing and an interiorcavity. The component assembly includes electronic circuitry 140, forexample, a circuit board and a display such as an LCD 130. A seal orspacer 120 according to an embodiment of the present invention is usedto eliminate any gap between the housing and the component assembly inthe direction of the stack-up (normal to the plane of the circuit board140).

The spacer 120 is made of a suitable material such as compressible foam.The body 122 of the spacer is a layer dimensioned to extend around theperimeter of the cavity at the front or back half of the housing. Acentral aperture 126 in the body enables the LCD 130 to be visiblethrough a window 112 in the front of the housing. The central aperturealso allows actuators 114 to contact or connect with correspondingelements on the circuit board 140.

Compressible features, such as the raised feature 124, are provided onthe front surface of the spacer. These compressible features make thespacer or seal hyperelastic as explained below. The raised features 124illustrated in FIG. 1 are domed, although they can be any suitable shapesuch as cylindrical, polygonal prism, conical, frusto-conical, pyramidaland frusto-pyramidal. Alternatively, a pattern of recesses, valleys ordimples can be cut, stamped or otherwise formed into the surface of thespacer, leaving compressible features (e.g. ridges surrounding the cutout portions) formed on the underlying body layer.

According to the present embodiment, the raised features 124 form aregular grid or arrayed pattern, however, any suitable pattern can beused. The planar density of compressible features can also be varied,for example by the pattern chosen, as discussed below.

The raised features 124 can be made of a material different than that ofthe spacer but, according to a preferred embodiment, they are integrallyformed with the spacer. The raised features 124 enable the spacer toaccommodate larger gaps than a conventional spacer without overcompressing the LCD 130 in smaller gaps.

As illustrated in FIG. 9, at the beginning of compression, the raisedfeatures 124 deflect with minimal force since the volume of the raisedfeatures 124 of the spacer 120 is small. See region 910 in FIG. 9.Without the raised features 124 there could be a gap or inadequatecushioning between the housing and the assembly. The raised features 124overcome the tolerance or gap without affecting the range of the workarea of the spacer 120. This makes the full compression range of atleast the body 122 of the spacer 120 available for cushioning thecomponent assembly. The component assembly will have neitherpre-compression set nor play.

FIG. 11 a illustrates a conventional spacer 1120 having thickness t. Inthis example, an acceptable maximum amount of compression c in the range0<c<=0.10t, i.e. any amount of compression up to 10 percent of theoriginal thickness of the spacer 1120 does not over compress the spacerand the spacer retains sufficient resilience to absorb a predefinedshock. Of course, the range will vary depending on many factors,including the properties of the material of the spacer and the geometryof the spacer, component stack and housing. In the example of FIG. 11 a,the spacer 1120 cannot accommodate gap g1 where g1>t. Also the spacer1120 cannot accommodate too small a gap g2 which overcompresses thespacer. Accordingly, the spacer 1120 can only accommodate gaps smallerthan its thickness, i.e. g<t, and if the acceptable maximum compressionis 10% then the spacer can only accommodate gaps larger than (1-0.1)t,or g>0.9t. Accordingly, for a conventional spacer such as the spacer1120, 0.9t<g<t, or more generally (1-c)t<g<t, where g is the size of thegap, t is the thickness of the spacer and c is the maximum acceptableamount of compression and 0<c<1.

By contrast, referring to FIGS. 12 a and 12 b, a spacer 1210 accordingto the present invention includes a main body 1212 with thickness t andprotrusions 1214 with thickness h. Assuming that the volume of materialin the protrusions is small compared with the volume of material in thebody, then the protrusions will be nearly completely collapsed beforeany substantial compression of the body 1212 occurs, as shown in FIGS.13 a to 13 c. When the protrusions are partially compressed, acompression force is exerted on the component stack preventing it frommoving in the stack direction. If there are fewer protrusions, thendeformation of the main body resulting from pressure on the protrusionsis negligible and the full range of compression of the main body 1212 isavailable to absorb any shock to which the component stack is subjected.Referring to FIGS. 12 a and 12 b, where the body 1212 of spacer 1210 hasthe same thickness as body 1120 and the same maximum amount ofcompression, then any gap which satisfies g<t+h and g>(1-c)t can beaccommodated, or (1-c)t<g<t+h. Thus, the spacer 1210 accommodates agreater range of gaps, including gaps up to a size of t+h instead ofgaps up to size t, without affecting the compression limit c. The ratioof h to t is important, and selected for a desired gap range. Forexample, the increase in gap range is very significant if h/t is closeto 1.

As indicated above, the maximum amount of compression, expressed interms of the total thickness of the spacer, can vary substantially.According to an embodiment of the present invention, the maximum amountof compression, c, is in the range 3% to 10%. According to anotherembodiment, c is in the range 4% to 6%. According to a furtherembodiment c is approximately 5%.

More generally, a spacer according to embodiments of the presentinvention includes a spacer having a body and layer of compressiblefeatures provided on the body. The body and the layer of compressiblefeatures have different compression properties. The body is relativelyresistant to compression and the layer of compressible features isrelatively easy to compress. This arrangement can be effected by usingdifferent materials or by using the same materials for differentlyformed structures or differently dimensioned structures as in theexamples above. According to the examples provided above, the bodycomprises a first layer relatively resistant to compression and theprotrusions form a sparse second layer of material that is relativelycompressible. Alternatively, the relatively compressible layer is formedof a layer similar to the body layer but having depressions, cut-outs,grooves or other volumes of material removed so that the total volume ofmaterial compressed is less than the volume of material compressed in alike volume of space.

Spacers according to aspects of the present invention have differentphysical characteristics than a conventional spacer. This is illustratedin FIG. 10. A conventional spacer without raised features has thecompression curve 1010 whereas a spacer according to an embodiment ofthe present invention has compression curve 1020.

The compression curves of FIG. 10 illustrate the different amounts offorce exerted on the LCD due to the compression of each spacer. It isevident that for a given amount of compression, spacers according toembodiments of the present invention advantageously exert less force ona component stack and, in particular, on an LCD or other sensitivecomponent in the component stack.

FIG. 2 illustrates another embodiment of the present invention, in whicha spacer 200 includes a body 220 having raised features 222 that aredifferently spaced than in the preceding embodiment shown in FIG. 1.FIGS. 3 and 4 illustrate still another embodiment wherein a spacer 300has a different pattern of raised features 310 on the body 320.

According to FIG. 5, an alternative embodiment of the present inventionis illustrated in which a front spacer 120 and a back spacer 510 areemployed, corresponding to each of the two halves 110 and 150 of thehousing. This provides additional protection for the components andenables larger tolerances to be overcome.

According to FIG. 6, the spacer 600 has raised features 610 on both itssurfaces. Again, this increases the amount of tolerance which can beaccommodated by the spacer.

FIG. 7 illustrates another pattern of raised features 710 which are lessdensely spaced on the body 720 of the spacer 700 than the raisedfeatures of FIG. 1. This decreases the volume of spacer 700 to becompressed and decreases the associated pressure. Alternatively, thepattern of compressible features can be more densely spaced to increasethe volume of material initially compressed and increase the pressure.

FIG. 8 illustrates compressible features 810 of varying heights thatmodify the compression curve of the spacer 800 over its area.

An example method of manufacturing the spacer of the present inventionis illustrated in FIGS. 14 and 15. Initially, a mass 1410 of liquidsolution of rubber or other suitable material is deposited on a plate1420, as shown in FIG. 14 a. As the solution cures, an oscillating blade1430 spreads the rubber solution 1410 over the plate 1420 to achieve alayer of rubber 1412 in a half-liquid state, as in FIG. 14 b. The layeris approximately twice the thickness of the final spacer, although thiscan be varied as required. Referring now to FIG. 14 c, a master roll1440 is then used to flatten and pattern the rubber 1412 and produce amass of material 1414 of the desired thickness, for example, 0.787 mmnot including the thickness of the raised features 1416. The material isallowed to cure, and is then trimmed to form one or more rolls which canbe cut as desired into individual spacers.

FIG. 15 illustrates an example embodiment of a master roll 1440 havingindentations 1442 which result in the raised features 1416. Of course,other master rolls are used to produce different shapes or patterns ofraised features, or to effect dimples or cut outs in a material roll forspacers.

The above-described embodiments of the present invention are intended tobe examples only. Alterations, modifications and variations may beeffected to the particular embodiments by those of skill in the artwithout departing from the scope of the invention, which is definedsolely by the claims appended hereto.

1. A spacer for use in a mobile device, the spacer for filling a spacebetween a component assembly and a housing, the component assemblyincluding a display component, the spacer comprising: a layer of foamfor insertion between the component assembly and the housing; the layerof foam including a plurality of cut-out portions to allow the layer offoam to be compressible upon assembly of the mobile device; the layer offoam used to space the component assembly inside the housing when themobile device is assembled, a depth of the layer, when uncompressed,exceeding the depth of the space between the component assembly and thehousing, and a depth of the layer, when compressed, exceeding apredetermined critical depth.
 2. The spacer of claim 1 wherein thecut-out portions are depressions, grooves, recesses, valleys or dimples.3. The spacer of claim 2 wherein the depressions are formed by cuttingor stamping.
 4. The spacer of claim 2 wherein the grooves are formed bycutting or stamping.
 5. The spacer of claim 2 wherein the recesses areformed by cutting or stamping.
 6. The spacer of claim 2 wherein thevalleys are formed by cutting or stamping.
 7. The spacer of claim 2wherein the dimples are formed by cutting or stamping.
 8. The spacer ofclaim 1 wherein the cut-out portions are stamped into the layer of foam.9. The spacer of claim 1 wherein the cut-out portions are cut into thelayer of foam.
 10. The spacer of claim 1 wherein the cut-out portionsare uniform in depth.
 11. The spacer of claim 1 wherein the cut-outportions are clustered in spaced apart groupings.
 12. The spacer ofclaim 1 wherein the layer of foam is provided with an aperture to exposethe display component.
 13. The spacer of claim 12 wherein the displaycomponent is one of a liquid crystal display, a plasma display, a lightemitting diode display and an organic display.
 14. The spacer of claim 1wherein the cut-out portions form a grid pattern.